cue: add a regression test for a structural cycle bug fixed in evalv3

The added bit of CUE incorrectly gives a result on evalv2,
but evalv3 correctly gives a structural cycle error.

Note that a lot of positions get unfortunately shifted
as we are adding an import at the top of the file.

Closes #3310.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I8b4bd4b1dda3ca7dadae242fb5489ecc1d980ec0
Dispatch-Trailer: {"type":"trybot","CL":1200808,"patchset":1,"ref":"refs/changes/08/1200808/1","targetBranch":"master"}